Intravenous (IV) paclitaxel is approved for the treatment of numerous cancers including MBC. Oraxol (Athenex, USA), is an oral formulation of paclitaxel in combination with a novel, orally active, potent and specific inhibitor of P-gp (HM30181A). Oraxol is expected to be less toxic with comparable efficacy to its iv counterpart. We report the interim results of an ongoing study of Oraxol in MBC patients.
Multicenter, single-arm, open-label, study of Oraxol (HM30181A at 15mg, plus oral paclitaxel 205mg/m2) administered orally for 3 consecutive days/week for up to 16 weeks. Paclitaxel PK was determined in the first and fourth week of Oraxol. Tumor Response by CT/MRI was measured using RECIST criteria 1.1 at weeks 8 and 16.
Sixteen MBC patients have been enrolled with a mean (range) age of 56.9 years (range: 38 - 79 yrs). Most had previous combination chemotherapies and/or monotherapy. There were seven (50%) partial responses and 7 (50%) with stable disease in 14 evaluable patients who had post-treatment CT scans. There was no progressive disease for the patients that reached 16 weeks of treatment. Three patients had treatment-related SAEs (grade ≥3 neutropenia); and there was 1 non-treatment related death. Preliminary PK results showed that the daily mean AUC of oral paclitaxel was similar at week-1 and week-4 (1397 vs. 1137 ng-hr/mL). Other studies have shown that oral paclitaxel can achieve exposure similar to that of IV paclitaxel.
Oral paclitaxel showed very encouraging activity in MBC patients with acceptable toxicity. PK of oral paclitaxel is reproducible.
Clinical trial identification
Legal entity responsible for the study
Athenex, Buffalo, NY.
G. Gerald Fetterly, D.L. Cutler, R. Kwan, D. Douglas Kramer, W-K. Chan: Sockholder and employee: Athenex. T. Hung: Stockholder: Athenex. All other authors have declared no conflicts of interest.